Device for gathering and conveying printed sheets straddling a gathering segment

CROSS REFERENCE TO RELATED APPLICATIONS

Priority is claimed with respect to European Patent Application No. 00810347.5 filed on Apr. 20, 2000, in the European Patent Office, the disclosure of which is herein incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a device for gathering and conveying printed sheets straddling a gathering segment. The device is formed by a conveyor apparatus that is loaded by sheet feeders disposed along a gathering segment, the apparatus having a saddle-shaped support surface for the printed sheets and driven carries.

Devices of this type are used in, for example, gathering and stapling machines, in which a stapling apparatus adjoins the gathering segment.

When the conveyor apparatus of a gathering segment is loaded, the printed sheets transferred by the sheet feeder are often not set down with their rear edge, seen in the conveying direction, at the associated carrier of the conveyor apparatus. Instead, the rear edges of the printed sheets fed by the sheet feeders are set down at a distance in front of sheets already on the conveyor. Or, the printed sheets are set down onto the conveyor apparatus askew due to the dynamic forces occurring upon impact with the carrier or due to a sudden halt in machine operation. Accordingly, the rear edges of the printed sheets fed by the sheet feeders do not align with the rear edges of the printed sheets being conveyed. Previous counteractive measures included slowing the printed sheets fed by the sheet feeders with elements such as brushes or springs that grip the printed sheets by the free-standing surface in a frictional connection and transfer them into a rear end position at the carriers. Often, the sliding behavior between the printed sheets and/or different format sizes will render the elements acting on the printed sheets through friction inadequate for uniformly arranging the printed sheets at the carriers.

In view of the above, it is an object of the present invention to remedy the described drawbacks with an advantageous device.

SUMMARY OF THE INVENTION

A device for gathering and conveying a plurality of printed sheets over a conveying path, each sheet having a front edge and a rear edge with respect to a direction of conveyance is provided. The device includes a conveyor device presenting a gathering segment and having a saddle-shaped support surface adaptable to be loaded by sheet feeders disposed along the gathering segment with a plurality of sheets that have legs straddling the saddle-shaped support surface; driven carriers disposed on the conveyor device and spaced apart from one another, wherein the rear edge of at least one of the sheets straddling the saddle-shaped support along the gathering segment is separated from an associated driven carrier; a guide apparatus arranged to raise at least one leg of the at least one sheet away from the saddle-shaped support surface; and a stop apparatus projecting into the conveying path of the at least one raised leg and gripping the front edge of the at least one raised leg, wherein the stop apparatus is removed from the conveying path by the at least one sheet.

The present invention considerably improves reliability of a common reference position of the printed sheets for further processing.

The present invention also includes a method for gathering and conveying printed sheets straddling a gathering segment, on which a plurality of sheet feeders is disposed. The sheet feeders consecutively load printed sheets onto a conveyor apparatus that comprises a saddle-shaped support surface and carriers that are secured to a circulating tension element. At least one leg of a printed sheet supplied to the gathering segment is held at a distance from the support surface, and the sheet is not placed onto the support surface until a stop apparatus acts on the front edge of the printed sheet.

Furthermore, it is possible to allocate the first sheet feeder only one stop apparatus, which grips the printed sheet lying on the support surface by the front edge of the one leg.

Because sheet feeders are exchangeable, it can also be practical to allocate a first sheet feeder an entire transfer apparatus.

In cases where the gathered printed sheets do not have a common defintion position at the end of the gathering segment, a stop apparatus associated with the gathering segment can project into the conveying path of the gathered printed sheets adjoining the last sheet feeder in the conveying direction.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described below by way of a preferred embodiment in conjunction with the drawings.

FIG. 1 is a side view of the device according to the invention.

FIG. 2 is a plan view of the device shown in FIG. <b>1</b>.

FIG. 3 is a cross section of the device along the line III—III in FIG. <b>1</b>.

FIG. 4 is a cross section of the device along the line IV—IV in FIG. <b>1</b>.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 and 2 illustrate the device <b>1</b> of the invention including a gathering segment <b>2</b> shown in a partial side view of a conveyor apparatus. The device gathers printed sheets, for example, in a gathering and stapling machine. The gathering segment is formed by a saddle-shaped, drivable or stationary support surface <b>4</b> and a conveyor apparatus <b>6</b> having carriers <b>5</b>, which are secured to continuously-circulating tension elements, for gathering and conveying printed sheets in a straddling position.

FIGS. 3 and 4 schematically illustrate an embodiment of a support surface <b>4</b>, in which a tension element <b>45</b> is saddle-shaped and has carriers <b>5</b>, which are secured to it with spacing from one another. The tension element <b>45</b>, which can be formed by a roller chain, runs on a guide rib <b>46</b> secured to a carrier <b>47</b>.

FIGS. 1 and 2 further illustrate a plurality of printed sheet feeders, with one being indicated by an arrow B, that load the gathering segment <b>2</b> consecutively with printed sheets.

FIGS. 1 and 2 depict the course of two printed sheets <b>3</b>, <b>7</b> from right to left according to the arrow F. Following the first printed sheet <b>3</b> transported from the right by the conveyor apparatus <b>6</b>, a second printed sheet <b>7</b> is set down by the sheet feeder B. At this stage, the rear edge of the second sheet <b>7</b> does not align with the rear edge of the first printed sheet <b>3</b>. The rear edges of the printed sheets must be aligned for further processing. The rear edges of the printed sheets are to be aligned against the carrier <b>5</b>. Further along the path, the printed sheet <b>7</b>′ has reached the end position on the conveyor apparatus <b>6</b>, and its rear edge <b>8</b> is now located at the carrier <b>5</b>′.

For executing the method of aligning the rear edges of the printed sheets against the carrier <b>5</b>, a sheet feeder (not shown) on the right side in FIGS. 1 and 2 positions a first printed sheet <b>3</b> astride the gathering segment <b>2</b>, and a carrier of the conveyor apparatus grips the rear edge immediately thereafter. Although relatively favorable sliding conditions exist between the support surface <b>4</b> and the first printed sheet <b>3</b>, the transfer apparatus of the invention can also be associated with the sheet feeders.

The printed sheet <b>3</b> reaches the operational region of the transfer apparatus <b>9</b> associated with the sheet feeder B, the region being marked by an arrow, and the front edge <b>10</b> of the one leg <b>11</b> has traveled between the support surface <b>4</b> and a guide apparatus <b>12</b> spaced from the support surface of the side. The guide apparatus <b>12</b> is adjustably connected to the base <b>14</b> of the device <b>1</b> by a carrier apparatus <b>13</b>. FIGS. <b>1</b>,<b>2</b> and <b>3</b> illustrate the elements used to adjust the guide apparatus <b>12</b>. A guide tab <b>15</b> serving to conduct compressed air, together with the support surface, from a lateral guide gap <b>16</b>, through which the conveyor apparatus <b>6</b> transports a respective leg <b>11</b> or plurality of legs <b>11</b> of printed sheets that were transferred by the upstream sheet feeders. The front end of the guide tab <b>15</b>, seen in the conveying direction, and the support surface <b>4</b> form a funnel-shaped intake opening <b>17</b>. Behind the intake opening <b>17</b>, a protruding plate <b>18</b> is vertically adjustable for adjusting the height of the guide tab <b>15</b> in a guide slot <b>19</b> of a downward-projecting lever arm <b>20</b>. The protruding plate <b>18</b> is secured to the outside of the guide tab <b>15</b>. For changing the guide gap <b>16</b> in terms of the distance from the guide tab <b>15</b>, the lever arm <b>20</b> is seated with its upper end in a support <b>21</b> secured to the base <b>14</b>. A set screw <b>22</b> serves in seating the lever arm <b>20</b> and is screwed to the support <b>21</b>. The set screw has a disk spring <b>23</b> that is tensed between the screw head and the lever arm <b>20</b> seated on the bearing segment. The lower end of the lever arm <b>20</b> is provided with a ball handle <b>24</b>.

The thread-side end of a hexagon-head screw <b>25</b> penetrates the lever arm <b>20</b> and impacts a stop surface <b>26</b> embodies at the support <b>21</b>. The screw <b>25</b> effects a change in the distance between the support surface <b>4</b> and the guide tab <b>15</b> during a rotation. As can be inferred from FIGS. 1 through 4, compressed air can be supplied to the guide gap <b>16</b> via the guide tab <b>15</b> embodies as a line. A bore <b>27</b>, extending up to the rear end of the guide tab <b>15</b> and over nearly the length of the guide tab <b>15</b>, is provided for this purpose. The line has discharge openings <b>28</b> for supplying compressed air with openings being provided at least in the rear region of the guide tab <b>15</b> and being oriented upward. The line is supplied via connected connecting bores <b>29</b> in the plate that is connected to the guide tab <b>15</b>. The connecting bores <b>29</b> are in turn connected to a connectable compressed-air source (not shown). Additional, downward-oriented discharge openings <b>39</b> of a separate bore <b>40</b> with a separate connector <b>41</b> and openings being distributed over nearly the entire length of the guide tab <b>15</b> can prevent a possible folding of the printed sheet corners, particularly those of the inside legs <b>11</b> hanging down, due to supplied compressed air.

The transfer apparatus <b>9</b> has a stop apparatus <b>31</b> at the end of the guide tab <b>15</b>. The stop apparatus <b>31</b> is for acting on the leg <b>11</b> of a printed sheet <b>3</b> that was lifted from the support surface <b>4</b> by the guide tab. The stop apparatus <b>31</b>, a component of the transfer apparatus <b>9</b>, has a stop <b>33</b> that can pivot on an adjustable carrier arm or support <b>32</b> that is connected to the base <b>14</b>. In the operating position, the stop <b>33</b> penetrates the conveying path of the leg <b>11</b> of a printed sheet <b>3</b> that hangs down. The conveying path extends approximately parallel to the gathering segment <b>2</b>. The stop apparatus is under the pressure of a torsion spring <b>34</b> counter to a pivot limit <b>35</b> on the carrier arm <b>32</b>. This action shifts the top printed sheet <b>7</b> so that its rear edge <b>8</b> rests against the carrier <b>5</b>′. The advancing motion of the conveyor apparatus <b>6</b> subsequently causes the front edge <b>10</b> of the printed sheet <b>7</b> to lift the stop <b>33</b> from the conveying path of the leg <b>11</b>, counter to the force of the torsion spring <b>34</b>, through a pivoting movement. The force of the torsion spring <b>34</b> is tensed at a screw <b>42</b> that constitutes the pivoting axis of the stop <b>33</b>. This force can be changed through the rotation of the screw <b>42</b>. The stop <b>33</b> can be adjusted both in height and laterally through a detachable clamp connection <b>36</b> (FIG. <b>4</b>).

At the end of the guide tab <b>15</b>, oriented in the conveying direction F, the tab has a recess <b>37</b>, into which the stop <b>33</b> projects in the operating position, so that the leg <b>11</b> affected by the impact can lie completely against the guide tab <b>15</b> until the impact.

For enhancing the rigidity of the leg <b>11</b> at the time of impact, a guide rail <b>38</b>, which holds the leg <b>11</b> against the guide tab <b>15</b>, is provided opposite the guide tab <b>15</b>, approximately at the height of the recess <b>37</b>. The guide rail <b>38</b> is adjustably secured to the support.

The invention has been described in detail with respect to preferred embodiments, and it will now be apparent from the foregoing to those skilled in the art, that changes and modifications may be made without departing from the invention in its broader aspects, and the invention, therefore, as defined in the appended claims, is intended to cover all such changes and modifications that fall within the true spirit of the invention.